Emotions can lead to involuntary physiological changes which suggests a co-relation between the two and there are quite a few theories that show this co-relation. Ekman, a biopsychologist, believed that emotions evolved because they support patterns of motor behaviour that were adaptive and prepared the organism for different actions. For example, fighting could have been the adaptive action in anger as blood flows increase to the hands. In other words, the subjective experience such as happiness, anger, fear creates physiological changes in the nervous system or endocrine system which then creates the associated behaviour including crying or running away. Similarly, Averill defined emotions as those ‘that fulfil vital biological functions’ which are needed for survival.
Psychologists have concluded through research that the physiological changes which occur are a main component of emotion and they are related. These changes involve the autonomic nervous system and the endocrine system. The nervous system can stimulate excitement and arousal, as well as relaxation and calmness which can be known as the fight, flight or frolic reactions. An interesting study was of Hohman (1966) who observed that male adults who had spinal cord injuries and suffered autonomic nervous system damage had significant changes in the nature and intensity of certain emotional experiences including anger and fear.
Research has demonstrated that many parts of the brain are specifically involved in the expression of different emotions. E.g. the frontal cortex and the limbic system are centres of aggression and fear. Researchers also found that people with emotions such as phobias may have a dysfunction in their prefrontal cortex which is then difficult to undo. Many hormones are involved in emotion, e.g. androgens are involved in aggression. An experiment which clearly shows the relation between emotion and biological changes is the one conducted by Valins and Laird where false feedback paradigms of posters still created an increase in heart rate of the participants.
Emotions consist of a conscious experience as well as physiological and neurological reactions which are either voluntary or involuntary. Sometimes when a strong emotion is recalled, such as fear, the same physiological changes occur which were present at the time of the emotion-this was theorized by LeDoux and depends on how strong the emotion was and how it was stored in the memory.
The James-Lange theory suggests that physiological arousal is enough for an emotional response to occur. They argued that our emotional experience is the result, not the cause of perceived physiological change. The crucial factor in the James-Lange theory is feedback from the bodily changes. They felt that we, humans, label our subjective state by inferring how we feel based on perception of our own bodily changes. Although Cannon disagreed to this- he felt that physiological arousal was not necessary for emotional experience-Schachter confirm the co-relation between emotion and physiology by conducting adrenaline experiment along with Singer and they got promising results supporting their theory of cognitive labelling. Dutton and Aron’s suspension bridge experiment supports Schacter’s experiment but then showed our labeling of our physical arousal can be mistaken.
Bowlby also verified that emotions and physiological changes are related as he demonstrated that those babies deprived of touch show retarded emotional and physical development. Whatever the theory, it is clear through the numerous examples that psychologists have gained evidence and do believe that the physiological mechanism and emotions are co-related.
Most of the emotions have similar physiological changes such as increase heart rate, increase in temperature and possibly sweating. Researchers such as Levenson et al. have even identified a small number of fairly reliable differences in patterns in the nervous system when negative emotions (anger, fear etc) are compared to positive emotions (happiness).
Even stress which can be considered as an emotion is related to the physiological mechanism as a large amount of stress can cause health related problems such as high blood pressure, ulcers and heart attacks. This is because the body reacts to emotions such as stress where the autonomic nervous system is activated in a process called the alarm reaction in the general adaptations syndrome.
In conclusion, there is a lot of evidence that supports the relation between emotions and physiological mechanism although it has been argued against by a few psychologists. Many of the theories have been altered as psychologists study other theories trying to come up with more accurate results. After researching, psychologists have realised that many of the emotions not only create physiological changes but are caused by the body including the brain, the nervous system and the endocrine system.